The unpleasant smell of liquid manure, particularly swine and chicken liquid manure, above all in applying the liquid manure during the fertilization of the fields is noticed very annoyingly. Likewise annoying is the development of irritating or harmful gases such as hydrogen sulfide, mercaptans and ammonia within the stable atmosphere if liquid manure is stowed there for a long time below split bottoms. For the protection of the environment, therefore, the elimination or reduction of the stench acquires an increasing significance. Additionally through higher harmful gas concentrations, there can occur with animals as well as with people working in the stables on occasion poisonous appearances, particularly through the effects of hydrogen sulfide or mercaptans.
To the solution of the problem of the reduction or elimination of the stench, there has already been extensive work. Thus, there have been considered both physical methods, as, e.g., aerating the liquid manure with aeration apparatus or units, as well as the addition of biochemical special products or chemicals.
While the aeration is relatively expensive, entirely apart from the odor annoyance of the environment during the aeration, by this aeration there can merely be produced a certain reduction in odor.
This is equally true for the addition of biochemical special products. In the addition of chemicals for the purpose of reducing odor there must be differentiated between masking an odor and the breakdown of the odoriferous materials to odor indifferent components.
Of course, a masking odor can bring about a certain effect in storage; however, the assumption therefore is that the liquid manure is not moved. Of course, there are not tied up thereby the undesired anaerobic fermentation processes which are the main cause of the unpleasant odor. As soon as the liquid manure is moved, which happens above all in bringing it out, the stench occurs reinforced.
Therefore, there are significant for the deodorizing only such additives with which it is possible to tie up the formation of irritant and harmful gases or to change into, or if they are already present, change them to harmless materials.
As has been shown by applicant's experiments, oxidation chemicals such as hydrogen peroxide, peracetic acid, sodium chlorate, sodium chlorite or the so-called peroxy compounds such as sodium peroxide, sodium percarbonate, potassium peroxymonosulfate, sodium peroxydisulfate, potassium peroxydisulfate, ammonium peroxydisulfate, percarbamide and peracetic acid do not bring about the desired effect.
Of course, there can be produced a certain reduction in the concentration harmful gas with several peroxy compounds such as potassium peroxymonosulfate or ammonium peroxydisulfate or percarbamide by using larger amounts, namely, at least 5 liters of 30% aqueous solutions per 1 m.sup.3 of liquid manure, but there is no reduction in odor.
With peracetic acid, there can be obtained a certain deodorizing activity but there occurs a strong odor of acetic acid, which apparently overlays the liquid manure odor.
In O'Neill U.S. Pat. No. 3,966,450, there is claimed the deodorization of suspensions of animal excrements with hydrogen peroxide in combination with strong mineral acids.
After that the odor of the animal waste should be reduced by treatment of the excrement with aqueous hydrogen peroxide solution in an amount of 5-500 ppm. of 100% aqueous hydrogen peroxide whereupon the pH value of the suspension is adjusted by addition of mineral acid to a pH of 4-8.
The reworking of this process, however, has had no success in the treatment of swine and poultry liquid manures.
Also by addition of higher amounts of hydrogen peroxide to the liquid manure there takes place solely, with strong foaming spontaneous, decomposition of the hydrogen peroxide. There could not be established a reduction in odor.
Besides the oxidizing chemicals, there has also been added formaldehyde as a taste checking material. Formaldehyde is mixed with liquid manure in the U.S.A., e.g., in the so-called Grazon-Process (see Cattle-Diets, Grazon, Champaign, Ill., 1975).
The use of aqueous formaldehyde solutions of various concentrations as well as the use of paraformaldehyde was not successful. This was also proven by our own experiments.
To be sure at higher additions of formaldehyde the odor of the liquid manure is partially masked by the pungent odor of formaldehyde, however, then simultaneously the mucous membranes are irritated. Because of the irritation of the mucous membranes, formaldehyde cannot be considered for a deodorization.
In German patent application P 26 40 364, 5 there is claimed the use of a combination of aqueous alkali chlorite or hypochlorite solution and aqueous formaldehyde solution for the deodorization of liquid manure.
The prerequisite for the process is that the alkali chlorite or hypochlorite solution and the aqueous formaldehyde solution be mixed into the liquid manure separate from each other.
To be sure with small additions of the above-mentioned aqueous solutions of these materials there can be produced a very good deodorizing effect. However, there is the disadvantage that by careless handling of formaldehyde and alkali chlorite solution there can be formed chlorine dioxide. For safety reasons, therefore, this combination cannot be considered to treat stables.
This deodorization system, therefore, can only be used for liquid manure stored (silo, preliminary pit) outside of stables which should be applied a short time later to the fields.
The purpose of the present invention is to develop a deodorizing agent which can be safely handled, which makes possible a good deodorization and elimination of harmful (noxious) gases but is not dangerous for people and animals.